The densely packed wires of this file card get into all the nooks and crannies and gently flick out the debris. Inexpensive but highly effective, we have found that the less pressure you use the better they work.
Some manufacturers recommend using a nail brush on rasps to prevent dulling the teeth. We believe that the teeth are at far greater risk from corrosion than abrasion, so a really effective clean with a file card removes all of the wood dust that would otherwise attract moisture from the atmosphere and hold it against the surface.
Wiping your rasps over with a bit of MetalGuard Ultra
after use will also help to keep corrosion at bay.